[ACCEPTED]-Instantiating anonymous object using C# object initializer syntax stored in string-dynamic

Accepted answer
Score: 21

Anonymous classes are C# syntactic sugar (see Remarks section here). csc.exe creates 12 a class with private fields and a read/write 11 property with the type inferred from context. All 10 uses of the object are, again, inferred.

What 9 this means is you cannot create an anonymous 8 class at run time because the CLR sees them 7 no differently than any other class (again, because 6 it is C# syntactic sugar).

So instead:

  • Use a Dictionary<string,object>
  • Use JSON.NET, XML or something like it that has some already-defined scheme for parsing a string to get an object. This requires the properties be well-defined, however.
  • Use System.Reflection.Emit to create the type at run-time, but I see no real benefit to this over just a Dictionary<string,object>

I also 5 have concerns of what you're doing because 4 this as a string very likely means to me 3 that you are accepting user input of some 2 kind. Be wary of the security issues in 1 whatever you do.

Score: 5

It's not possible using anonymous types, however 2 you can do it with Reflection Emit using 1 the TypeBuilder class, specifically TypeBuilder.Create(..).


Score: 5

The best way to do it is to use serialization. But 11 of course, that doesn't use the same string 10 format that you described.

Your object initializer 9 does not have to contain constant values.

string myName="bob";
int myAge=30;
double mySalary=100000;

object empData = new { name = myName, age = myAge, salary = mySalary };

So 8 in your scenario you would have to parse 7 out the individual elements from your string, and 6 perform some conversions on them to coerce 5 them into the types you want.

If you are 4 not married to this particular string format, you 3 can serialize and deserialize your objects 2 and accomplish the same thing using XML 1 much more easily.

Score: 2

There's no direct easy way to do so. Basically, you 7 have these options:

  1. Parse the string manually.
  2. Use the C# compiler to compile that object as a part of an assembly and use reflection to figure out the contents.
  3. (not sure if it's possible, C# 4.0 only): Use C# 4.0 managed compiler classes to parse the expression and infer the stuff.

None of which is ideal 6 in my opinion. I'd consider QueryString 5 like pairs, XML or JSON or some other format 4 that has parsers available out there instead 3 if you have the option and consider storing 2 data in a dictionary instance instead of 1 creating an object for every expression.

Score: 1

I don't think this question answers yours 11 per se, but it will tell you why it's not 10 possible to create anonymous instances of 9 objects using strings in a manner such as 8 you suggest:

How do I create and access a new instance of an Anonymous Class passed as a parameter in C#?

Anonymous types don't have any 7 public fields, consequently while you can 6 do this for a named object, it's not so 5 simple to do it for an anonymous type. That 4 said, there's nothing to stop you [as suggested 3 by BFree] using reflection to emit the MSIL 2 for the anonymous type - which isn't exactly 1 straightforward, but isn't impossible either.

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